Hi Paula! I think your experience is very normal, even just generally for a last semester college student. COVID certainly didn't help anything, and indeed I think many of us - of all ages, and both students and educators - are still recovering from the experience. I recently started a new degree program and the struggle is very real.
Unfortunately I don't think there's a magic answer to make everything better. It sounds like you're already doing some of it - keeping on top of things to avoid getting buried underneath instead. Something that usually helps me is to remember that there is a finish line. This is not forever - you have a graduation date, you just need to get there. It's a cliche, but - 'This too shall pass'.
Set realistic, concrete, short term goals for yourself - grade those tests, read 'x' number of pages, write the next section of that paper - and then reward yourself when you accomplish them. Keep the rewards proportionate to the task; binge watching 4 hours of Netflix is not a suitable reward for 30 minutes of grading (I only say that because I have been there!).
I haven't tried it, but I read about a '10 minute' method: work for 50 minutes, then take a 10 minute break. Then work for 40 minutes, then take another 10 minute break. Then 30 minutes, 10 minutes...etc. This set of 'diminishing returns' helps accomodate your shortening attention span while still allowing you to get a good amount of work done.
Just some ideas. I'm sure others have plenty more. Good luck, and keep at it! You've got this!